1. Field of the Invention
The present application is based upon German patent application no. 197 01 761.4, filed on Jan. 20, 1997, which is hereby incorporated by reference. The invention relates to a self-locking lock with a bolt, a lock swing catch, an auxiliary swing catch and a slide plate, in which the bolt and the lock swing catch move outwardly into a locking position due to a spring-load and are locked with the door closed, and in which the bolt in the case of the open door and in the completely retracted position is arrested by the auxiliary swing catch via the slide plate, and by pressing in the auxiliary swing catch on closing the door, the arresting of the bolt is cancelled and the bolt moves out into a locking position.
2. Discussion of the Related Art
DE 44 07 244 C1 describes a self-locking lock with a changer, a bolt-movable into the closed position by a spring, a swing catch and an auxiliary swing catch, in which the bolt operable by means of a split latch nut or a lock cylinder can be arrested in the open position by means of a catch releasable by means of the auxiliary swing catch. An unintended extension of the bolt with the door open is prevented in that a second pivoted lever, controlled by the swing catch, is provided for blocking the auxiliary swing catch, and the latter is blocked in the extended position by the pivoted lever when the swing catch is also extended.
Although this lock has proven satisfactory in practice, it can occur that in intermediate states the bolt is extended but does not pass into the opening of the locking plate. This can, e.g., arise due to a springing back of the door in the case of an uncontrolled closure onto excessively strong door seals. It is also not completely possible to exclude problems if, in the case of an authorized door opening from the outside, the door handle does not remain pressed down to the complete opening of the door and the bolt moves forward again without being able to engage in the locking plate.
In the case of a self-locking door lock described in EP 668 425 A1, a bolt is guided in a guide link of a push rod, the latter being displaceable linearly against the tension of a biasing spring and the bolt is drawn into the lock. A safety catch which, e.g., has a catch rod located on the push rod and a tiltably mounted catch plate, engages in such a manner on the push rod that the bolt is arrested in each withdrawn position. With the aid of a position sensor projecting out of the door lock it is possible to release the safety catch and, under the action of the biasing spring which acts on the push rod, the bolt can move out into a locking position.
This known lock is particularly intended for burglar-proof locks with several blocked bolts. The linear push movement is used as a particularly easy transfer for the secondary locks. However, the bolt is arrestable in the end portion of its withdrawal movement in each withdrawal position, so that the bolt is not completely retracted into the lock box, and so the door can only be opened in the case of a wide air gap between frame and door.